Interactions of phytochrome and exogenous gibberellic acid on germination of Lamium amplexicaule L. seeds

Summary In henbit (Lamium amplexicaule L.) seeds, micromolar levels of gibberellic acid (GA₃) introduced at the onset of imbibition markedly stimulated germination. Sensitivity to GA₃ stimulation is rapidly lost if the seeds are pretreated in darkness at 15° for 1 day or more on a water substrate. Loss in responsiveness to GA₃ is hastened by pretreatment in far-red or by dark pretreatment at higher (25°) temperatures and is reduced by pretreatments at 5°. A portion of the lost responsiveness to GA₃ at 15° or higher is attributable to onset of a secondary dormancy, but the results of far-red treatment at 5°, where secondary dormancy is not a factor, clearly indicate that some phytochrome in the far-red absorbing form increased the effectiveness of gibberellic acid action.Abbreviations GA gibberellin - GA₃ gibberellic acid - R red light - FR far-red - P_r red-absorbing form of phytochrome - P_fr far-red-absorbing form of phytochrome Mention of a trade name or proprietary product does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable     

Steroidal glycosides from the roots of Cynanchum amplexicaule Sieb. et Zucc

Seven new steroidal glycosides (amplexicosides A (4), B (7), C (8), D (9), E (10), F (11), and G (12)), along with six known compounds (cynatratoside A (1), tylophoside A (2), cynatratoside B (3), glaucogenin A (5), glaucoside A (6), and hancoside A (13)) were isolated from the 95% ethanol extract of the roots of Cynanchum amplexicaule (Sieb. et Zucc.). Their structures were determined based on spectral and chemical evidence. Compound 12 has a 14, 15-secopregnane-type skeleton aglycone, which has not been reported in literature.     

Seed Coat Structure and Histochemistry of Abelmoschus esculentus. Chalazal Region and Water Entry

The seed coat structure and histochemistry of Abelmoschus esculentuswere studied by bright-field, fluorescence and scanning electronmicroscopy. The seed coat was typical of species of the Malvaceae.The endotesta cells had inner tangential walls which were verythick and autofluorescent. The occurrence of phenolic substancesat this level has been related to seed coat imposed dormancy.The palisade cells were composed of three differently shapedparts: an upper ‘prismatic part’, a medium ‘transitionpart’ and a lower ‘twisted part’. The formerwas rich in hydrophilic substances, the latter was lignified.The swelling of the ‘prismatic parts’ was relatedto seed coat cracks. The region controlling onset of water entrywas thought to be the chalazal area. Thanks to the presenceof a large amount of highly acidic polysaccharide, water wasable to penetrate from the permeable maternal tissue, throughthe chalazal cap and plug as far as the boundary between thepalisade and underlying mesophyll. During imbibition of watera kidney-shaped ‘blister’ was seen to rise, formedby separation of the palisade cells from an underlying singlelayer of subpalisade cells. The palisade layer forming the blisterroof showed the same histochemical characteristic of other seedregions. The single layer of the blister floor showed an affinitywith Toluidine Blue O and Alcian blue. Both blister roof andfloor were strongly autofluorescent. Abelmoschus esculentus (L.) Moench, okra, seed coat, chalazal region, water entry, structure, histochemistry     

木兰科种子内种皮合点区形态观察

在扫描电镜下观察了１０属３２种木兰科植物种子内种皮合点区的形态,发现可分为孔状和具管的窝状两大类型,且在不同的属种间有所差别,可以用来作为木兰科分类的新依据     

木兰科种子内种皮合点区形态及其系统学意义

在扫描电镜下系统研究了木兰科10属52种成熟种子内种皮合点区形态。该形态分为孔型和管型两大类。孔型为内种皮合点区具一小穿孔。木莲属Manglietia、香木兰属Aromadendron、盖裂木属Talauma(8种)、南洋含笑属Elmerrillia和鹅掌楸属Liriodendron具此类型。管型由内种皮合点区向下凹陷形成的小窝和由窝底向外伸出的小管组成。华盖木属Manglietiastrum、盖裂木属Talauma(3种)、长蕊木兰属Alcimandra、含笑属Michelia、合果木属Paramichelia和观光木属Tsoongiodendron具此类型。在木兰属部分种中还观察到两种形态之间的过渡类型。上述形态特征在属内稳定并为木兰科植物所特有,而且明显表现出原始类群的合点区形态大多为孔型,进化类群的合点区形态大多为管型的特点。     

A New Species of Polystichum Roth from N. Burma and S. W. China

Polystichum adungense ching et Fraser-Jenkins is described as new from N. Burma and S. W. China